Streptococcus suis Meningitis in Swine Worker, Minnesota, USA

To the Editor: Streptococcus suis is a major bacterial pathogen in swine worldwide. Historically, cases in humans have occurred sporadically , mostly in Asia (1,2). However, an outbreak in China involved 215 human cases and 39 deaths (3). Only 3 human cases of S. suis disease were documented in the United States before 2011: 2 domestically acquired cases in New York and Hawaii, and 1 case in a person in California who was probably exposed in the Phil-ippines (4). We describe a case of S. suis disease in a swine worker in Minnesota, USA. The case-patient was a previously healthy 60-year-old man (truck driver). On December 14, 2011, severe headache and chills developed, which he attributed to the onset of influenza. He had a history of migraine headaches , and used prescription medications to treat his headache. However, on December 15, he awoke with a severe headache that was unresponsive to treatment. Despite having to stop his truck several times because of the severe headache, he successfully completed his delivery route. Early on December 16, his wife drove him to a nearby emergency department after he did not respond to ordinary commands. The patient had reduced coordination and behaved aggressively. His blood pressure was 92/52 mm Hg. He underwent intuba-tion for 24 hours for airway protection, and a lumbar puncture was performed. Cerebrospinal fluid (CSF) had a leukocyte count of 10,501 cells/mL (99% neutrophils), a protein level of 509 mg/dL, and a glucose level of 38 mg/dL. A few gram-positive diplococ-ci were observed in CSF. Complete blood count showed a leukocyte count of 14,800 cells/mL (92% neutrophils), a hemoglobin level of 14.1 g/dL, and a platelet count of 157,000/mL. Strep-tococcus suis was isolated from CSF and 2 of 4 blood cultures. Identification of S. suis was confirmed by using 16S rRNA gene sequencing at the Minnesota Department of Health. The patient was given decadron, ceftriaxone, ampicillin, vancomycin, and acyclovir. During hospitalization, antimicrobial drugs were tapered until he received only ceftriaxone. Major symptoms were severe headache and nausea. He was discharged in good condition on day 10 of hospitalization and then completed a 14-day course of ceftriaxone. There are 35 known serotypes of S. suis (1). Of these serotypes, se-rotype 2 is most commonly identified in infected swine and humans (2). The S. suis isolate from this patient was identified as serotype 2 by coaggluti-nation test at the International Reference Laboratory …